This invention relates to visors for use with motor vehicles and more particularly to an improved visor including means for reducing the aerodynamic drag of the visor.
Visors for use with motor vehicles are generally well-known. Such devices are useful for shading the windshield and the driver of the vehicle to thereby improve visibility for the driver. Visors have also been provided in various colors and finishes for decorative effect. A basic visor comprises a generally rectangular sheet of usually opaque material having ends connected to the vehicle at the sides of the windshield and/or having one of the long edges attached to the vehicle along the top edge of the windshield. The other long edge of the sheet is usually positioned by suitable means below and in front of the top of the windshield.
Most vehicles and their windshields are designed to provide somewhat laminar flow of wind over the windshield and the rest of the vehicle to reduce aerodynamic drag when the vehicle is driven at highway speeds. It is quite apparent and well-known that when a conventional visor is attached to the vehicle for its intended purpose, it also acts as an air brake and interferes with the flow of air from the windshield over the top of the vehicle. For highway operation of the vehicle, such as a van or truck, this increased air drag can cause a substantial reduction of fuel mileage and proportional increase in operating costs.
Thus, it is seen that while the use of external visors on motor vehicles is desirable, the aerodynamic drag of such devices is a definite problem.
It is known that some attempts have been made to vent air trapped under the visor. One known attempt was to provide a single large vent near the vehicle body at the center of the visor. Such a vent cannot provide a smooth air flow over the vehicle nor relieve the trapped wind condition over the entire length of the visor.